01 - Preheat oven to 350°F.
02 - Combine graham cracker crumbs, sugar, and melted butter in a bowl. Press mixture firmly into a 9-inch pie dish, covering the bottom and sides evenly.
03 - Bake crust for 8 minutes until lightly golden. Let cool slightly on a wire rack.
04 - Whisk egg yolks and lime zest in a medium bowl for 2 minutes until pale. Slowly whisk in sweetened condensed milk, then add lime juice and salt. Mix until smooth and slightly thickened.
05 - Pour filling into the cooled crust. Bake for 12 minutes until the center is set but still slightly wobbly in the middle.
06 - Remove from oven and cool to room temperature, then refrigerate for at least 3 hours until completely set.
07 - Beat heavy cream, powdered sugar, and vanilla extract with an electric mixer on medium-high speed until soft peaks form.
08 - Spread or pipe whipped cream over the chilled pie. Garnish with extra lime zest if desired.